Thanks for the info.
After doing some research, I found this under Michigan laws:
(3) An ordinance or regulation enacted under subsection (1)(a), (d), (e), (f), (g), (i), or (j) shall not be enforceable until signs giving notice of the local traffic regulations are posted upon or at the entrance to the highway or street or part of the highway or street affected, as may be most appropriate, and are sufficiently legible as to be seen by an ordinarily observant person. The posting of signs giving the notice shall not be required for a local ordinance which does not differ from the provisions of this act regulating the parking or standing of vehicles; nor to ordinances of general application throughout the jurisdiction of the municipalities enacting the ordinances which prohibit, limit, or restrict all night parking or parking during the early morning hours, if signs, approximately 3 feet by 4 feet, sufficiently legible as to be seen by an ordinarily observant person, giving notice of these ordinances relating to all night parking or parking during the early morning hours, are posted on highways at the corporate limits of the municipality.So, according to that, if there is not a 3 ft by 4 ft sign at the "corporate limits of the municipality" (city limits?) then the ticket can't be enforced, right? Any idea how I find out the corporate limits of the municipality?